1. Field of the Invention
The invention relates to a computer-aided surgery apparatus. More specifically, the invention relates to such an apparatus which aids a surgeon in accurately positioning surgical instruments for performing surgical procedures on a patient.
The invention also relates to a linkage mechanism for connecting a fixed point on a portion of interest of a patient (for example, a fixed point on a leg or arm of a patient) with a fixed point on the apparatus, and for maintaining a fixed separation between the fixed points, whereby, to maintain a fixed relationship between the portion of interest of the patient and the apparatus even when the portion of interest of the patient is being moved.
2. Description of Prior Art
Many surgical procedures, particularly in the fields of orthopedic surgery and neurosurgery, involve the careful placement and manipulation of probes, cutting tools, drills and saws amongst a variety of surgical instruments.
There are available mechanical apparatus which are used for different surgical procedures to help the surgeon guide the surgical instruments to ensure proper alignment. These alignment mechanisms must be referenced to certain anatomical landmarks and the set-up time for the various alignment jigs can represent a significant portion of the total surgical duration.
When surgical procedures are required on, for example, unexposed tumors or the like, fluroscopy is used to indicate to the surgeon the position and orientation of the surgical procedure. This has the disadvantage of exposing a patient and physician to radiation. In addition, the accuracy is less than adequate for precision requirements of the surgery.
In addition, in procedures relating to the cutting of boney parts for the purposes of joint replacement, fracture repair or deformity correction, among others, there is the problem of tool orientation such as drilling from point to point, sawing, locating planes in specific orientations with other planes of specific orientations, etc. The problems of 3-dimensional control of the surgical instruments becomes formidable. As above mentioned, some jigs exist for the performance of limited procedures permitting safe and reproducible orientation of tools. However, these have the disadvantage of being less than adaptable to variations that occur during surgical procedures. In addition, the limits of inaccuracy permissible for satisfactory results during surgery leave many of the currently accepted techniques for surgical instrument control unacceptable.
Although the field of 3-dimensional imaging as represented in the techniques of MRI (magnetic resinence imaging) and CAT scans (computer aided tomography) provide an abundance of 3-dimensional information concerning the locations of, for example, unexposed tumors, there is presently no interface between this information and the surgical processes which provide remedies. Required is an apparatus which can transpose the information of the 3-dimensional imaging systems from the reference system of the 3-dimensional imaging systems to a reference system of the apparatus.
U.S. Pat. No. 4,473,074, Vassiliadis, Sep. 25, 1984, teaches a device providing a laser beam in the performance of microsurgical procedures. The apparatus of the '074 patent does not have the facilities for providing electronic feedback of 3-dimensional information from 3-dimensional imaging systems for the purposes of presentation and feedback to the surgeon to thereby complete a feedback loop necessary to make full use of the instrument in sophisticated procedures. In addition, the device of the '074 patent can be used only to direct a laser beam at an exposed target, so that it is not applicable for surgical procedures on unexposed portions of a patient.